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LCROSS (Lunar Crater Observation and Sensing Satellite), which will travel to the moon aboard the launch vehicle for the Lunar Reconnaissance Orbiter (LRO), will test for the presence of water beneath the lunar surface by crashing a pair of heavy impactors into one of the permanently shadowed craters at the Moon’s South Pole. The impact will create a plume of debris that can be analyzed for the presence of water using specialized instruments. Dr. Anthony Colaprete, who is an expert on the Martian climate system, is principal investigator for the LCROSS mission.

NASA Tech Briefs: You are NASA’s principal investigator for the Lunar Crater Observation and Sensing Satellite, also known as LCROSS. Tell us about that project and what it’s designed to do.

Dr. Anthony Colaprete: LCROSS is a secondary payload to the Lunar Reconnaissance Orbiter (LRO). It is to launch later this year on an Atlas 5 rocket to the moon. The physical purpose for the LCROSS mission is to investigate a permanently shadowed region at the South Pole of the Moon.

About 10 years ago the Lunar Prospector spacecraft detected enhanced hydrogen concentration at the poles of the Moon and there’s speculation that this enhanced hydrogen is in the form of water ice trapped in the lunar dirt. The LCROSS mission principally is to excavate some of this lunar dirt from one of these permanently shadowed craters, lift it into sunlight so we can see it, and investigate whether or not this enhanced hydrogen is in the form of water, or some other mineral form, and to broadly understand what the characteristics of the lunar dirt is in one of these permanently shadowed craters. Since we’ve never been to the poles of the moon, we just want to understand more broadly if it is similar to what we saw at the Apollo landing sites, for example.

NTB: The plan is to crash both parts of the LCROSS spacecraft, first the 2-ton rocket booster, followed later by the command module, known as the “shepherding spacecraft,” into a crater on the Moon. How fast will they both be traveling at the moment of impact?

Dr. Colaprete: They’ll both be moving at approximately 2.5 kilometers per second.

NTB: The impact of the rocket booster is expected to create a plume of debris that could rise as high as 40 km above the surface of the moon. The shepherding spacecraft will then fly through this debris and analyze it for traces of water using a sophisticated array of onboard instruments, correct? Won’t the heat generated by the crash alter the properties of some of the elements in that debris?

Dr. Colaprete: A small portion. It’s kind of a fallacy that impacts are hot. Certainly parts of the impact are hot, but the vast majority of the material that is lifted up from the lunar surface is going to be at approximately the temperature it was before the impact.

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